Home Random Page


CATEGORIES:

BiologyChemistryConstructionCultureEcologyEconomyElectronicsFinanceGeographyHistoryInformaticsLawMathematicsMechanicsMedicineOtherPedagogyPhilosophyPhysicsPolicyPsychologySociologySportTourism






EXPLORING FOR PETROLEUM

Locating petroleum. Knowing that petroleum traps exist is one thing, but pinpointing traps far below the earth’s surface is quite another. Many methods have been used to locate petroleum traps, but the most important methods are aerial surveying, geological exploration, geophysical (seismic) exploration and exploratory drilling.

Aerial and satellite. Surveys from high altitudes give a broad picture of a geographic area of interest. Major surface structures such as anticlines and faulted regions can be clearly observed by these methods. This information helps locate areas where more detailed study is warranted. In the early years of petroleum exploration, visualization from an aircraft or mapping river and creek drainage patterns were successful surveying techniques. Modern aerial and satellite surveying is more sophisticated allowing a number of features to be evaluated, including thermal anomalies, density variations, mineral composition, oil seepage and many others.

Surface geological exploration.

Observations by trained geologists of rock outcrops (where subsurface layers reach the surface), road cuts and canyon walls can identify lithology and assess the potential for hydrocarbon source rocks, reservoir-quality rocks and trapping mechanisms in an area under study. Much has been learned about ancient deposits from studying modern river deltas, for example. Detailed geologic maps, made from these observations, show the position and shape of the geologic features and provide descriptions of the physical characteristics and fossil content of the strata.

Geophysical exploration. Through the use of sensitive equipment and analytical techniques, geophysicists learn a great deal about the subsurface. Chief among these techniques is seismic exploration in which shock waves, generated at the surface and aimed downwards, are reflected back to the surface as echoes off the strata below. Because rocks of varying density and hardness reflect the shock waves at different rates of speed, the seismologist can determine depth, thickness and type of rock by precisely recording the variances in the time it takes the waves to arrive back at the surface. Continual improvements in seismic measurement and the mathematical methods (algorithms) used to interpret the signals can now give a clearer “picture” of subsurface formations. Other geophysical methods use variations in the earth’s gravity and magnetic properties to detect gross features of subsurface formations.

 


Date: 2015-02-28; view: 1169


<== previous page | next page ==>
THE MIGRATION AND TRAPPING OF PETROLEUM | Drilling for Petroleum
doclecture.net - lectures - 2014-2024 year. Copyright infringement or personal data (0.006 sec.)